On the effect of unrestrained trailing edge morphing on NACA0012 airfoil aeroelastic response: A CFD approach

Trailing edge morphing technology offers strong potential for enhancing the aerodynamic performance of airfoils under varying flight conditions. This study investigates the effect of trailing edge deformation (50% of the chord) on the aeroelastic response of a NACA0012 airfoil, focusing on parameters such as lift, drag, flutter behavior, and overall stability. A fully coupled fluid–structure interaction (FSI) approach is employed, solving the Navier–Stokes equations using URANS, combined with a finite element model of the airfoil structure. Simulations were conducted across different values of dimensionless stiffness k * and stiffness ratios φ , representing the Young’s modulus relationship between the morphing and rigid segments, to analyze the influence of morphing on the dynamic response of the system. The results show that low stiffness configurations exhibit amplified oscillations and stall-flutter phenomena, whereas higher stiffness values lead to a damped response. A dynamic instability region was identified for k * < 270 . The optimal configuration ( k * = 2.50 , φ = 0.1 ) yields a mean drag reduction of approximately 86 % compared to the fully unstable case, with a lift-to-drag ratio c l / c d ranging between −30 and 30, while the unstable configuration ( k * = 2.48 , φ = 0.1 ) produces peak drag coefficients above c d = 0.1 due to massive flow separation. These findings establish that unrestrained trailing-edge morphing accelerates flutter onset rather than suppressing it, demonstrating that passive morphing alone is insufficient and must be combined with active stiffness control to exploit the aerodynamic benefits of flexible trailing edges.